The units are just in 'pixels'. If you acquire the image with a camera you would have to find the dimensions of one pixel on your own, perhaps by using a reference (e.g. I know this object is 1.0cm long) or perhaps by some more complicated calculation if you use lenses to focus an image onto a digital camera. Manufacturers' datasheets give pixel sizes for most digital cameras, I believe, which would be one part of that calculation. It is true that without having a pixel-to-distance conversion the program doesn't help much.

Hey Joel. I looked into your source and found that you have misunderstood how the correlation length can be obtained from the auto-covariance. You are using the FWHM of the fit. The correlation length is the value of the integral itself.

The units are just in 'pixels'. If you acquire the image with a camera you would have to find the dimensions of one pixel on your own, perhaps by using a reference (e.g. I know this object is 1.0cm long) or perhaps by some more complicated calculation if you use lenses to focus an image onto a digital camera. Manufacturers' datasheets give pixel sizes for most digital cameras, I believe, which would be one part of that calculation. It is true that without having a pixel-to-distance conversion the program doesn't help much.

Hi Joel,
Can you please help me how proceed to play with your Speckle Size via autocorrelation. My question is do I have to make GUI.
Thanks for the help
Surya

Hey Joel. I looked into your source and found that you have misunderstood how the correlation length can be obtained from the auto-covariance. You are using the FWHM of the fit. The correlation length is the value of the integral itself.

Hello Joel,
I'm trying to run your function but for some reason i get this error:
% ??? Undefined function or method 'xcov' %for input arguments of type 'double'.
% Error in ==> SpeckleSize at 46
% s=size(xcov(E)); %finds the % size of the autocovariance array
Do you have any idea why do i get this error?
(P.S I'm using MATLAB2010B)
Thank you,
Ariel.

The units are just in 'pixels'. If you acquire the image with a camera you would have to find the dimensions of one pixel on your own, perhaps by using a reference (e.g. I know this object is 1.0cm long) or perhaps by some more complicated calculation if you use lenses to focus an image onto a digital camera. Manufacturers' datasheets give pixel sizes for most digital cameras, I believe, which would be one part of that calculation. It is true that without having a pixel-to-distance conversion the program doesn't help much.

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